Catch more LDAP errors on authentication
Catch more LDAP errors on authentication

In addition to catching the INVALID_CREDENTIALS exception which is
thrown when invalid credentials are entered, also catch
ldap.INVALID_DN_SYNTAX and ldap.UNWILLING_TO_PERFORM which are thrown
when leaving both username and password resp. one of them empty when
authenticating.

plajjan/NIPAP,SpriteLink/NIPAP,plajjan/NIPAP,ettrig/NIPAP,bbaja42/NIPAP,SoundGoof/NIPAP,ettrig/NIPAP,garberg/NIPAP,SpriteLink/NIPAP,garberg/NIPAP,fredsod/NIPAP,fredsod/NIPAP,ettrig/NIPAP,plajjan/NIPAP,SpriteLink/NIPAP,garberg/NIPAP,ettrig/NIPAP,SoundGoof/NIPAP,SpriteLink/NIPAP,SoundGoof/NIPAP,bbaja42/NIPAP,plajjan/NIPAP,ettrig/NIPAP,plajjan/NIPAP,plajjan/NIPAP,fredsod/NIPAP,garberg/NIPAP,garberg/NIPAP,garberg/NIPAP,bbaja42/NIPAP,fredsod/NIPAP,SoundGoof/NIPAP,SpriteLink/NIPAP,bbaja42/NIPAP,bbaja42/NIPAP,bbaja42/NIPAP,ettrig/NIPAP,SoundGoof/NIPAP,SoundGoof/NIPAP,SpriteLink/NIPAP,fredsod/NIPAP,fredsod/NIPAP